The egg is very nutritious and wholesome food. It is also known that egg yolk is one of the richest sources of cholesterol eaten by man. Because of concern in the recent past over the possible involvement of cholesterol in atherosclerosis, and the high level of cholesterol in egg yolk, the consumption of eggs has fallen markedly.
Even though the chicken egg has one of the lowest levels of cholesterol of all the domestic birds, a considerable amount of work has been done in an attempt to reduce the level of cholesterol in the chicken egg. Some have tried to reduce the cholesterol in the yolk by feeding various oils. Others have tried substituting sitoserol for cholesterol in the yolk. The use of drugs to inhibit cholesterol biosynthesis has also been tried. None of these strategies ever proved successful enough to be accepted commercially.
The inability of the researchers to come up with low cholesterol shell eggs gave impetus to substitute the natural yolk with a synthetic yolk-like substance in liquid egg, see for example U.S. Pat. No. 3,840,683 issued Oct. 8, 1974 to Strong et al.
Much data has been published indicating the level of cholesterol in various strains of chickens and avian species, however that data resulted from methods that were not specific for cholesterol but in fact measured cholesterol, related compounds and in some cases even triglycerides. A recent evaluation of the cholesterol level of some species of eggs using a more specific colorimetric test revealed the following data:
Species Cholesterol (mg/gm yolk) ______________________________________ Chicken 9.9 Bobwhite Quail 11.0 Araucana 12.2 Hungarian Partridge 13.0 Ringneck Pheasant 13.5 Wild Turkey 13.7 Turkey 15.8 ______________________________________